Cup of comfort

Cup of comfort

来源：未知 作者：晁渺 时间：2019-03-07 03:14:03

By Emma Young Research into the effects of caffeine in mouse brains suggests that drinking coffee really can protect against Parkinson’s disease. Earlier epidemiological studies in the US found that people who drank four cups a day were less likely to develop the disease. But some researchers suggested that something about people who are more prone to Parkinson’s disease also makes them less likely to drink coffee. Now a team at Massachusetts General Hospital has found evidence that caffeine blocks key receptors on cells in the part of the brain affected by the disease. The study does not prove that caffeine can prevent or treat the symptoms of Parkinson’s, says researcher Jiang-Fan Chen. “But the epidemiological research has shown a clear relationship between moderate caffeine consumption and a reduced risk of Parkinson’s. Now our findings clearly favour the idea that caffeine has a neuroprotective effect,” he told New Scientist. Parkinson’s is caused when brain cells that produce dopamine mysteriously die. The team gave mice a chemical that kills dopamine-producing cells. But mice that were also given the equivalent of one or two cups of coffee per day retained near normal dopamine levels. They also had far fewer Parkinson’s-like symptoms. The team found that caffeine blocked the binding site of A2A receptors. These receptors are on cells in the substantia nigra, and are targeted by dopamine. However, Chen says the team does not yet understand how blocking the receptors prevents the loss of cells that produce dopamine. The team now plans to study people with Parkinson’s, to examine whether the disease progresses more slowly in patients that drink more coffee. But if it does – and if further research confirms the effects are down to blocking A2A receptors – scientists will want to develop drugs that target these receptors only, says Chen. This would reduce side effects. “Pharmacologically, caffeine is a dirty drug,” he says. “We would want something that specifically targets A2A receptors.” Robert Meadowcroft of the Parkinson’s Disease Society in the UK says: “Although this study offers positive results, coffee in large quantities can be a harmful substance and could lead to additional medical problems.” More at: Journal of Neuroscience (21: